My Polarized Eating & Training Experiment

This is a documentation of my personal experiment using the Polarized Training Approach with “Polarized Nutrition”, to lose weight, keep FTP improvements and most importantly improve ultra endurance performance.

I’m sharing this experiment because I have not found a great conclusion around polarized training, fat adoption and intermittent fasting. I wanted to do something experimental during the preparation of a 24-hour mtb race coming up on June.

Just for the context of the experiment:


  • I wanted to set an age category course record on the golden24 race and i need to increase ftp, shed some weight and somewhat improve performance without relying on 80g carb for the entire race to keep moving
  • I needed to reorganize my rides because of family commitments and also improve volume of training
  • Keep the whole training doable, simple, easy to manage and predictable from life stress and other problems

Just for context:

  • 45 years old masters guy 183 pounds ~333 FTP (~4w/kg)
  • i have been on TR since 2017
  • I got some burnout before with some endocrine issues so i’m pretty careful
  • I work 10 hours mostly zoom meetings from home
  • Have 4 kids
  • data nerd with devices to track everything
  • Diet is high quality balanced food with precise injection of shakes when carbs needed


I wanted to get better for the 24 race this year and I checked the limiters. After 14hours I could not execute the carb based nutrition plan and I had to drop performance to finish safely. I did some 14 hours rides multiple times and I felt that I was fully dependent on the carb intake and my fat utilization was not there. I won the race last year, and I was very calculated and sustained but I feel there is a lot to gain there to be able to crack the 16 lap record.

I made some research and things clicked together when I read about how ultra endurance runners are focusing on fat adaptation. From here I got to the controversial keto diet topics and landed on the intermittent fasting area.

The bottom line was that I would be able to use fat for fuel so much more efficient on low intensity (24 hour is really like 0.55 IF) but I also need to be efficient on carbs because MTB is punchy. The way to get it was keto (no go for me), intermittent fasting (align with my goals) and fasted rides. I have found the intermittent fasting a great structure to cut the afternoon snacks/binging and carb dependency.

I have done several blocks of Sweet Spot / Polarized base and build plans and I felt that I got FTP benefits from the polarized approach AND being mentally easier to push through the weeks and months.

I thought what if I would mix the polarized training plan with a polarized eating plan… to get best of two worlds.

The idea was to do a complete training block to align the polarized training with a polarized fueling strategy. Do morning fasted endurance rides (3x) and fueled high intensity rides (2x) afternoons then throw a long rides over the weekend. The idea was to train the mitochondria to use fat but don’t forget to use carbs. Polarized training (low intensity with high intensity) mixed with very specific polarized diet (low carb for low intensities and high carb for high intensities). This would help to shed some weight but I was not sure how much power will be lost or whether I can increase FTP with this model or simply how the fasting and fasted rides will effect my endocrin system and mood and health.

I decided to do a constant intermittent fasting to deplete carbs if possible before morning rides. I decided to stop eating after 6pm so when I started the morning rides I would be 12hours out food.

It was the plan:

  • Monday - rest
  • Tuesday - high carb diet - afternoon vo2 workout - low carb post ride
  • Wednesday - fasted morning ride - balanced meals
  • Thursday - fasted morning ride - high carb recovery
  • Friday - high carb diet - afternoon threshold workout - low carb post ride
  • Saturday - fasted morning ride - balanced meals
  • Sunday - balanced meals - long ride - balanced meals

I used myfitnesspal to count food to make sure I know cause and effect. I used whoop to check hrv, recovery and sleep related metrics to have some guard rails.

I used high volume base polarized and I extended the morning workouts to 2 hours. I do some cross country skiing so those were sparkle in.

I have just finished the 2x high volume sweet spot blocks in Nov/Dec and gained 5w and 4w FTP over two blocks over 2 months. My system got used to ~10-12 hours of training.

Here are the lessons learned week by week.

Week 1.

  • the early 6;00 eating was easy did not have issue of hunger
  • I started eating during fasted rides around after one hour in
  • I got 2-3 days of pretty wild blood sugar rushes and some irritability
  • Day 4-5 got zero hunger as i ate 8:00 am till 6:00 window and with usually 1,500-2,000 extra calories were basically just eating every few hours
  • I hit all workouts but high intensity was very hard (i have done sweet spot before some blocks so it was new)
  • I used perkins-1 2 hours in morning and i was able to think and work (type etc) so time just flied also 1,400 calories off
  • I could not rely on any hunger sensations so I simply timed the food on time

Bottom line: got used to the rhythm pretty quickly and I slept way better.

Week 2.

  • the high intensity workouts became hard only
  • I needed to supplement the carbs and proteins to make sure things are good
  • I started really enjoying the fasting and as I read more the more I liked it. The general consensus i found was that if you don’t eat all the time then your body get used to use reserves not just what is coming from the stomach… that helps to consume older cells and sources could just sit there for years…
  • Over the weekend I got to ride my son for a basketball competition and i rode 10am - 2pm fatbike completely fasted (16 hours) and ate 3 hours in the ride with no problem

Week 3.

  • dropped like 6 pounds over 3 weeks
  • Morning rides were very good a lot of work and stuff. I realized when i did rides after work i watched netflix but in the morning i always did some more beneficial and got way more motivated
  • I set a goal to try a 6 hour ride fasted no food around 0.65 if to see what can be done
  • Interesting thing was that i slept more and my recovery got really good and all time high HRV and very low moring heart rates

1st block Checkpoint:
FTP AI detection from 333w to 339w that is all time high for me. I got down from 83kg to 78kg (4.01w/kg to 4.37w/kg) during the time. I was able to ride 0.65if for 3 hours fasted no problem. So the general assumptions were validated: increase FTP / Fat Adaptation / Lose weight. The question was how sustainable it is for longer and when to dial back to keep the momentum without pushing over the boundaries.

Week 4. Recovery week

  • it was interestingly more difficult as i dropped a bit of the focus of the food
  • I did a ton of volume still but no intensities
  • On Sunday I felt a bit of hitting a wall
  • I think the mistake here I made was not reducing the volume of even low intensity rides… I got too excited… and I felt I started to dig in a hole

Week 5.

  • I was curious how the vo2 will go but luckily things got back on track
  • I wanted to test a complete 24 hour fasting to see how my body reacts…
  • I ate before the Tuesday vo2 session and i did not eat anything after then I did the morning ride and thought i keep not eating until I was hungry so i basically dropped the whole day
  • After that day i made a 3 hours empty and that two throw things off substantially- got very hungry and kinda irritated so i noted not to overdo stuff
  • I got red recovery and some weird carb cravings on Thursday
  • I got poor sleep and got some low recoveries all week (work related stress and might be some overdo)
  • The threshold workouts felt great too on Friday but I decided to take an easy weekend as the volume was a bit too much
  • I got an early ride on Saturday, sleep got back on track and easy Sunday before the full day off

This is where I am right now…

  • Weight loss part done not so much more I want further
  • FTP went up and I did not get compromised on the higher end
  • Performance is more sustainable when I don’t fuel that much
  • Balance and monitoring is critical for health

I feel this is when this has to modulate back to a sustained effort. Reduce the fasted rides and the volume to keep the body to recover. The data shows and I feel that after week 5 it started adding up. So now switch from the overdose a bit would be the strategy to keep the gained advantages.

I’ll do the experiment further and keep it posted if it has any interest. I can share whoop files also to see recoveries.